I'm not particularly enamored with the protesters, or with the way that Thai politics have basically degenerated into different groups paralyzing the capital, taking turns bringing the country to a halt. Moreover, the protesters have turned down an offer of early elections, which is about the most generous offer the government is likely to make. I have no real sympathy for them or their cause, even if there was some nobility to it once.
However, this extreme measure by the government would have done nothing to bring the problems to an end, and instead would have been a horrifying escalation. Moreover, it would have inflamed sympathy towards these protesters and badly hurt the people living in the areas about them. Here's hoping this moment of level-headedness spreads.
Immediate edit: Never mind, the Thai army is moving in with armored vehicles to isolate the protesters after all.